In fields including cell biology and immunology, development of analytical techniques for evaluation and quantitation of cellular protein expression and secretion profiles is of significant importance to elucidate underlying biochemical processes and cell signaling mechanisms. Due in part to the heterogeneous behaviors often exhibited by cells, a need exists for tools and procedures capable of assaying large numbers of discrete cell populations that are also suitable for detection of biomolecules at the single cell level. Sensitive and accurate assessment of cellular phenotypes and functionalities as well as identification of drivers and interactions between individual cells have been shown to be important indicia of the capabilities and operation of biological systems.
As one example, immune cell response is directed by a large number of secreted proteins including cytokines, chemokines, and growth factors which represent important functional regulators mediating a range of cellular behaviors and cell-cell signaling processes. Monitoring these complex immuno-signaling pathways and cellular interactions present significant challenges to identifying clinically relevant measurements that can be used to understand that state of the immune system, predict clinical outcomes, and direct treatment or therapies. Increasingly, there is a demand for sensitive and highly-multiplexed technologies for cellular analysis that can be used to identify and rapidly evaluate correlatives of disease, cellular responses to various chemicals and therapeutic agents, and other cell-based processes involved in immunological interventions. Such technologies can also be used to better understand the underlying mechanisms of immunity.